Soul Harvestors

Soul Harvestors are aberrant creatures previously created by Necrophitus Arkane when he had control of the Obelisk of Spirits that resides in the Spirit Realm. The Obelisk was an object allowed him to mutate the denizens of the Spirit Realm, and in corrupting the Soul Guardians, created the Soul Harvestors.
These creatures exist to devouring the wandering spirits of the Spirit Realm. Luck be on the side of the denizens of Arawyn that these aberrant monsters cannot interact with the Material World and are constrained to their own plane.